This article describes a number of syndromes affecting the nail unit. When a patient presents with a complaint involving the nails, it is important to consider first the common nail disorders. However, one should evaluate the entire patient to discover associated signs or symptoms that would point toward an underlying syndrome. The dermatologist may have an opportunity to discover a syndrome that might have significant related morbidity or mortality, which may be prevented through early detection. By recognizing the presence of inherited syndromes, the dermatologist may facilitate genetic counseling. It should be noted that most of the syndromes described are of autosomal dominant inheritance, with variable expressivity, and that the individual manifestations can vary widely in severity, making recognition difficult.